Caution signal



FIG. 1 is a perspective view of a caution signal incorporating my new design. The dotted lines do not form any part of the invention;

FIG. 2 is a front elevational view of the caution signal;

FIG. 3 is a right side elevational view of the caution signal, with the left side being a mirror image thereof;

FIG. 4 is a top plan view of the caution signal;

FIG. 5 is a rear elevational view of the caution signal; and,

FIG. 6 is a bottom plan view of the caution signal. 

The ornamental design for a caution signal, as shown and described. 